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This paper reviews the impact that the emerging pervasive "sea of devices" may have on the task of service provisioning and introduces Whale, an architecture that enables an application not only to vary the format of the content generated for each particular device, but also allows the author to define a device-specific view on the application's data and features, thus providing optimal application interaction for each device. Whale achieves this through the strict separation of content presentation from content generation, using JavaServer Pages(TM) and JavaBeans' technologies, and by creating Whalelnvoker as an enhancement of WebSphere"", which dynamically selects and executes the appropriate combination of JavaServer Pages and JavaBeans to satisfy a data request from an end-user device. The paper also describes the first commercial deployment of the Whale architecture-Swissair's Easy Check-In service.
Pervasive computing enables a broad range of end-user devices to access data and applications on servers, much like today's PC (personal computer) access to HTML (HyperText Markup Language) sources across the Internet. However, these new form factors differ from the conventional HTML-centric PC, not only with regard to their input and output capabilities, but also, and more significantly, in the way they interact with the user. This includes alternative modalities (such as voice) as well as alternative usage patterns (such as mobility). The common feature among those devices is their browser-centric architecture: content is transmitted from the server to the client in the form of a marked-up document, and all interaction between the users at the client device is orchestrated through a user-interface that, although controlled by the server through the marked-up document, is generated and maintained by a browser program that is independent of the server and its application and resides permanently on the device. The user interface itself is not necessarily display-based, but may very well be a voice interface. Such browser devices are also frequently referred to as "thin" clients, not because the browser infrastructure on the device is necessarily thin or the device is compact in size or has limited storage or memory, but because the application is maintained exclusively on the server. Apart from simple caching, no aspect of the application is resident on the client beyond individual request-reply boundaries.
In this paper, a review is...